Communications networks have multiple traffic types. Some traffic types require Quality of Service (QoS) support, such as real-time/buffered video. Traffic types having QoS demands are known collectively as QoS traffic. Some other traffic types do not require any stringent QoS support, such as downloading, email, etc. Traffic types having no QoS demands are known collectively as Best Effort (BE) traffic.
The role of traffic engineering in a communications network is to direct traffic from sources to their corresponding destinations. This typically involves finding one or more paths from the flow source to the flow destination and splitting the flow among the one or more paths for all flows in the communications network. A flow can be identified by a source-destination pair. A flow often has a demand, i.e., rate requirement. A source-destination pair along with its flow demand is called a commodity. The links of the communications network have limited capacities.
Traffic engineering is intended primarily for QoS traffic to satisfy individual traffic requirements of QoS flows. Known traffic engineering techniques which handle mixed traffic scenarios in which both QoS and BE traffic are present typically consist of performing traffic engineering for all QoS flows using all available network resources, calculating the remaining network resources after routing and traffic splitting decisions have been made for all QoS flows, and performing traffic engineering for BE flows using the remaining network resources. Traffic engineering techniques which better handle mixed traffic scenarios are desired.